The invention relates to a dissection instrument for surgical operations.
During surgical operations, cuts made in the tissue cause blood vessels to become injured. The emerging blood impairs visibility for the surgeon, and it is also important to minimize loss of blood by the patient. A typical example of an operation that frequently involves severe bleeding is tonsillectomy.
To stanch bleeding, the patents DE 41 39 029 A1 or DE 37 10 489 A1 disclose coagulation devices with which a high-frequency current is caused to flow through a noble-gas atmosphere between an electrode and the tissue, by ionizing the noble gas and thus producing a plasma. As a result of the heat thereby generated, the tissue is coagulated. Such a device must be used in addition to the dissection instrument.
The patent WO 93/01758 discloses a coagulation device in which a dissection instrument, a needle, scissors, loop or the like is movably disposed in a conduit for the noble gas, so that the operator can move the arrangement after it has been placed within an endoscope. In this case the dissection instrument is employed either entirely mechanically, e.g. as a cutting tool, or as an electrosurgical instrument by production of a direct flow of current between the instrument and the tissue. Furthermore, in this known arrangement the surgical instrument can be used as electrode to generate a plasma, as is likewise the case for the objects of the documents cited above. The manipulation of the known instrument during coagulation is very critical, because it is absolutely necessary to avoid contact between the instrument, while in use as an electrode, and the tissue, so that the latter is not locally destroyed. In addition care must be taken not to switch the coagulation current on accidentally during the dissection, because then the current would act on the tissue by direct conduction through the instrument. Elaborate measures must be taken to ensure this temporal separation of the two functions.
The object of the invention is to disclose a simple dissection instrument for surgical operations that is extremely user-friendly while functioning in an improved manner.
It is an essential point of the invention that the disclosed arrangement enables substantially simultaneous dissection and coagulation with one and the same instrument. Thus it is possible practically during the cutting to stanch the bleeding that is caused, or to close tissue, with no increased manual effort. As a result, the duration of the operation is considerably decreased, blood losses and hence the disadvantages cited above are diminished or even prevented, and nevertheless the demands made on the operator are reduced.
Preferably the working instrument as a whole is made of a plastic, a ceramic or a similarly insulating material, which is relatively simple with regard to manufacturing technology. Alternatively, or where appropriate additionally in certain sections, the working instrument can be coated with a plastic or ceramic material or the like, so that there is no possibility of a flow along the instrument to the tissue of an electrical current that might interfere with the flow of the coagulation current from electrode to tissue.
An important aspect here is the fact that during plasma coagulation it happens automatically, so to speak, that the xe2x80x9cadmissionxe2x80x9d of a current is possible only into those parts of the tissue that have a sufficiently high conductance. This sufficiently high conductance is simultaneously also a measure of how xe2x80x9copenxe2x80x9d or moist the tissue is at its surface. As soon as an adequately large coagulation effect has been achieved, so that the surface of the tissue is xe2x80x9cdryxe2x80x9d, the coagulation current seeks another path or is interrupted, if the controllable HF source is appropriately (with respect to voltage and/or current) adjusted. The insulated working instrument can thus not disturb this xe2x80x9cself-regulationxe2x80x9d. Preferably the electrode device, which comprises an electrode holder and an electrode, in particular a wire electrode, is disposed close to the working instrument and preferably is fixed thereto. This enables a simple and nevertheless particularly compact construction, so that the coagulation current can flow very directly to the tissue sections in which the working instrument is making changes at that moment.
The gas-supply apparatus comprises an outflow opening of a gas conduit that is disposed close to the working instrument, next to or surrounding the electrode device. This feature, again, leads to an especially simple and compact construction.
The dissection instrument can be made particularly simple, stable and small if the working equipment and the electrode holder are constructed substantially in one piece. In this case, the gas outlet is preferably also integrated into the working equipment.
It is further advantageous for the working equipment and at least a distal end section of the holding device to be constructed substantially in one piece.
The electrode device is preferably constructed and disposed in such a way that direct electrical contact between the electrode device and the tissue is prevented. This can be achieved, for example, in the case of an electrode disposed in the gas outlet by positioning the electrode some distance behind the opening. It is also possible to surround the electrode itself with a protective cage or the like, to prevent direct contact with the tissue.
The stream of noble gas should be xe2x80x9csoftxe2x80x9d enough that it has no mechanical effect and also that only a very small amount of gas is consumed, as the presence of large amounts of gas would be highly disadvantageous in various sites of application. In order nevertheless to be able to remove liquid, tissue fragments or other solids from the tissue surface with no supplementary instruments, in particular to expose the operation field and achieve a better coagulating action, it is possible to provide in addition (where appropriate, also made integral with the devices described previously) equipment such as suction, blowing or rinsing devices. For instance, in addition to the gas conduit for supplying ionizable (noble) gas to produce the coagulation current, a gas nozzle can be provided to blow liquid away. A simultaneous extraction by suction, for instance through an additional channel, is likewise possible. It will be self-evident that several channels can serve various functions in alternation, such as a rinsing and a suction function.
Furthermore, it is possible to provide additional supplementary electrosurgical instruments, such as an electrode in a needle, spherical or flat configuration, or else a wire loop, in order to perform special functions (e.g., polypectomy).
Preferably the holding device is exchangeable, with simultaneous coupling and decoupling of the gas and current supplies, so that while the coagulation conditions are maintained (with respect to gas and current flow) the working instrument can be changed.
To ensure coagulation conditions as nearly optimal as possible, it is advantageous for cleaning means to be provided to keep the electrode device free of liquid or similar substances that could make it dirty or alter the current flow. In particular when the electrode device is disposed within the gas outlet, the electrode can be kept free by ensuring that a substantially continuous (very slight) gas stream flows around the electrode device.